Solitary Toxic Adenoma Research Articles

Preoperative Preparation in Hyperthyroidism and Surgery in the Hyperthyroid State.

Hyperthyroidism is a clinical condition that develops due to the excessive production and secretion of thyroid hormones by the thyroid gland, leading to an elevated concentration of thyroid hormones in tissues. Hyperthyroidism is characterized by low TSH and elevated T3 and/or T4, with the most common causes being Graves' disease, toxic multinodular goiter, and solitary toxic adenoma. T3 is the peripherally active form of thyroid hormone, affecting nearly each tissue and system. The most prominent aspects of hyperthyroidism are related to the cardiovascular system. The treatment of hyperthyroidism includes three options: antithyroid drugs (ATDs), radioactive iodine therapy (RAI), and surgery. Among these treatment modalities, surgery is considered as the most effective one. For patients who are candidates for surgery, preoperative preparation is required to ensure that the thyroidectomy can be performed under optimal conditions. Preoperative preparation should be a combination therapy aimed at preventing the synthesis, secretion, and peripheral effects of thyroid hormones from the thyroid gland. Medications that can be used in this treatment include thionamides, beta-blockers, iodine, corticosteroids, cholestyramine, perchlorate, lithium, and therapeutic plasma exchange. These treatment options can be combined based on the patient's condition. While it is recommended that patients be made euthyroid through preoperative antithyroid treatment to prevent the feared complication, which is the thyroid storm, the supporting evidence is limited. Preoperative treatment does not prevent against thyroid storm whether the patient is euthyroid or hyperthyroid during surgery. Whether surgery should be delayed until biochemical euthyroidism is achieved in hyperthyroid patients remains a topic of debate. Recent studies suggest that thyroidectomy can be safely performed during the hyperthyroid phase by experienced anesthesiologists and surgeons without precipitating thyroid storm or increasing intraoperative and postoperative complications. Although achieving the euthyroid state before surgery is ideal in hyperthyroid patients, it is not always possible. Factors such as allergies to medications, drug side effects, treatment-resistant disease, patient noncompliance, and the urgency of definitive treatment are critical in determining whether hyperthyroidism can be controlled preoperatively. When surgery is necessary in hyperthyroid patients without achieving euthyroidism, the patient's overall condition and comorbidities should be evaluated together by the anesthesiologist, surgeon and endocrinologist, with particular attention to stabilizing the cardiovascular system. We believe that in hyperthyroid patients who are cardiovascularly stable during the hyperthyroid phase, thyroid surgery may not need to be delayed and can be performed safely.

Radiofrequency ablation for autonomously functioning nodules as treatment for hyperthyroidism: subgroup analysis of toxic adenoma and multinodular goitre and predictors for treatment success

PurposeTreatment of hyperthyroidism caused by autonomously functioning thyroid nodules (AFTN) with 131I often leads to undesirable hypothyroidism. Radiofrequency ablation (RFA) has emerged as a promising alternative. This retrospective analysis aimed to examine the efficacy of, and postprocedural hypothyroidism after, RFA for AFTN.MethodsPatients with hyperthyroidism caused by AFTN and treated with RFA were included if follow-up of at least 1 year was available. Cure was defined as thyroid medication–free biochemical euthyroidism. To predict cure, patient and treatment factors were analysed. A distinction was made between solitary toxic adenoma (STA) and toxic multinodular goitre (TMG).ResultsForty-eight patients (36 STA, 12 TMG) were included. One year post-RFA cure rate was 72% in STA versus 25% in TMG (p = 0.004). One patient developed hypothyroidism. In 11 patients that remained hyperthyroid, a second RFA was successful in 83% of STA and 40% of TMG patients. At last available follow-up, this amounted to a total cure rate of 81% in STA and 33% in TMG (p = 0.002). In STA, cured patients had a higher baseline TSH and a lower FT3 than non-cured patients (p = 0.026 and 0.031). Cure was observed in 91% of patients when > 2.1 kJ/mL was delivered during RFA, compared to 44% when less energy was administered.ConclusionThe efficacy of RFA was nearly 3 times higher in STA patients compared to TMG. Severity of hyperthyroidism and kJ/mL delivered during RFA predicts cure. Direct comparison to the current standard of care is needed to implement RFA in treatment of hyperthyroidism caused by AFTN.

Radioiodine treatment outcome by dosimetric parameters and renal function in hyperthyroidism

BackgroundHyperthyroidism has been treated with radioiodine therapy for eight decades, with known benefits and side-effects. No consensus exists on which activity dosage and pre-therapeutic measurements are required for optimal treatment, balancing risk of incomplete response, therapy-induced hypothyroidism and radiation exposure. A retrospective analysis was performed to assess these questions.MethodsData was collected on radioiodine treatment outcomes for 904 patients treated for Graves' disease or toxic nodular goitres at our institution during 2016–2020. The prescribed absorbed doses were 120 Gy (Graves’ disease), 200 Gy (toxic multinodular goitre) and 300 Gy (solitary toxic adenoma). Univariate analysis and multivariate regression modelling were used to find factors linked to treatment outcome.ResultsThe cure rate of hyperthyroidism after one administration of radioiodine was 79% for Graves' disease, 94% for toxic multinodular goitre and 98% for solitary toxic adenoma. Thyroid mass, uptake and effective half-life were all significantly associated with cure in Graves’ disease, but not in toxic multinodular goitre. The rates of therapy-induced hypothyroidism were 20% and 29% for toxic multinodular goitre and solitary toxic adenoma. Neither the cure rate nor the hypothyroidism rate was found to be superior among patients with individualised effective half-life measurements in toxic nodular goitres. Poor renal function was associated with dubious iodine uptake measurements but was not found to correlate with worse outcome.ConclusionsMultiple measurements of individual iodine uptake for kinetics estimation may be unnecessary, and a population-based value can be used instead. Patients with renal impairment had similar outcome as other patients, but with a higher risk of dubious uptake measurements.

Current approach to surgical management of hyperthyroidism.

Hyperthyroidism is a set of disorders that involve excess synthesis and secretion of thyroid hormones by the thyroid gland, which leads to thyrotoxicosis. The most common forms of hyperthyroidism include diffuse toxic goiter (Graves' disease), toxic multinodular goiter (Plummer disease), and a solitary toxic adenoma. The most reliable screening measure of thyroid function is the thyroid-stimulating hormone (TSH) level. Options for treatment of hyperthyroidism include: antithyroid drugs, radioactive iodine therapy (the preferred treatment of hyperthyroidism among US thyroid specialists), or thyroidectomy. Massive thyroid enlargement with compressive symptoms, a suspicious nodule, Graves' orbitopathy, and patient preference are indications for surgical treatment of thyrotoxicosis. This paper reviews the current literature and controversies on the surgical approach to the management of hyperthyroidism.

Serum thyroid stimulating hormone level for predicting utility of thyroid uptake and scan

ABSTRACT Background Thyroid uptake and scan (TUS) is a clinical tool used for differentiation of thyrotoxicosis etiologies. Although guidelines recommend ordering a TUS for evaluation of low TSH levels, no specific value is defined. This study aimed to determine a TSH cutoff at which TUSs yield a greater likelihood of successful determination of etiology to avoid unnecessary testing. Methods This was a retrospective study on 137 patients seen by an endocrinologist who underwent TUS for evaluation of low TSH (<0.4 μU/mL). A receiver operating curve analysis was performed to determine the TSH cutoff with maximal sensitivity and specificity for prediction of diagnostic utility. Results Ninety percent of TUSs (n = 123) led to a diagnosis, while 10% (n = 14) were inconclusive or normal. Diagnoses included Graves’ diseases (52%), toxic multinodular goiter (19%), thyroiditis (12%), and solitary toxic adenoma (7%). The median TSH value was 0.008 μU/mL (IQR 0.005, 0.011), and the median free T4 value was 1.7 μU/mL (IQR 1.3, 2.8). The ROC analysis produced an area under the curve of 0.86. The optimal TSH cutoff value was 0.02 μU/mL (sensitivity 80%, specificity 93%) for prediction of diagnostic yield. Conclusion This study demonstrates that TSH is a useful predictor of the utility of TUS in yielding an etiology of thyrotoxicosis. Our analysis showed that TUS had a greater likelihood of determining an etiology when TSH was ≤0.02 μU/mL. This information can help clinicians avoid unnecessary cost and patient time burden when TUS is unlikely to aid in determining the etiology of thyrotoxicosis.

Radioiodine Therapy-Induced Conversion of Toxic Adenoma to Graves’ Disease

We present a 50-year-old female who was evaluated for the symptoms of thyrotoxicosis. She had low thyroid stimulating hormone (TSH) 0.02 with normal free thyroxine (FT4) 1.00 (0.61-1.76 ng/dL) and normal total triiodothyronine (TT3) 1.0 (0.60-2.20 ng/mL) levels. Her thyrotropin receptor antibody (TRAbs) and thyroid peroxidase antibody (TPOAb) titers were negative. Thyroid ultrasound revealed an ill-defined, heterogeneous, 1.8 cm x 0.8 cm x 0.7 cm nodule in the left lower lobe. 123-radioiodine (RAI) thyroid scan revealed 38.5% uptake, which was concentrated in the lower left thyroid lobe, a finding consistent with a solitary toxic adenoma of the thyroid.The patient became clinically and biochemically euthyroid on methimazole (MMI). She then underwent 131-RAI therapy with 12 mCi, which cured her hyperthyroidism with normalization of TSH levels for four months. She then developed overt thyrotoxicosis with low TSH of 0.02, elevated TT3 of 3.2, and normal FT4 of 0.91. Repeat TRAbs and TPOAb were elevated along with diffusely increased uptake on the I-123 RAI thyroid uptake scan, consistent with Graves’ disease (GD). The patient was then placed on MMI again to bridge to definitive treatment with total thyroidectomy. Our case is a rare case where the patient with solitary toxic adenoma with negative TPOAb serology developed GD following I-131 RAI treatment.

Changes in subtypes of overt thyrotoxicosis and hypothyroidism following iodine fortification

To investigate the impact of mandatory iodine fortification (IF) on the incidence of nosological subtypes of overt thyrotoxicosis and hypothyroidism. We identified and scrutinized all possible new cases of overt thyrotoxicosis and hypothyroidism in an open cohort in Northern Jutland (n=309434; 1 January 1997) during the years 2014-2016. Individual medical history was evaluated to verify and detail the incidence of overt thyroid dysfunction and for classification into nosological subtypes. A number of cases were excluded during final verification due to spontaneous normalization of thyroid function, as they had no medical history suggesting a known condition, which could transiently affect thyroid function (subacute/silent thyroiditis, PPTD and iatrogenic thyroid dysfunction). An identical survey was conducted in 1997-2000 prior to mandatory IF of salt (13µg/g) that was in effect from year 2001. The standardized incidence rate (SIR) of verified overt thyrotoxicosis decreased markedly from 97.5/100000/year in 1997-2000 to 48.8 in 2014-2016 (SIRR: 0.50 [95% CI: 0.45-0.56]). This was due to a distinct decrease in the SIR of multinodular toxic goitre (SIRR: 0.18 [0.15-0.23]), solitary toxic adenoma (SIRR: 0.26 [0.16-0.43]) and to a lesser degree Graves' disease (SIRR: 0.67 [0.56-0.79]). SIR for overt hypothyroidism was unaltered by 2014-2016 (SIRR: 1.03 [0.87-1.22]). However, age distribution shifted with more young and fewer elderly cases of verified overt hypothyroidism. Mandatory IF caused a substantial reduction in SIR of verified overt thyrotoxicosis (especially of nodular origin) while avoiding an increase in SIR of verified overt hypothyroidism.

Salt iodization halves risk ofthyrotoxicosis in Denmark.

A study in Danish adults over the period 1997–2016 reports a 50% reduction in thyrotoxicosis caused by multinodular toxic goiter, solitary toxic adenoma or Graves disease after the introduction of mandatory salt iodization. During the same period, there was no significant increase in overt hypothyroidism.

Previous Live Births and Induced Abortions May Precede Later Development of Graves’ Hyperthyroidism

Objective: To investigate the association between reproductive history and later development of various nosological subtypes of overt hyperthyroidism. Study Design: From the Danish population, we included incident hyperthyroid women, and for each case we recruited 4 euthyroid age-sex-region-matched controls from the same sub-population. Hyperthyroid cases/controls were: Graves’ disease (GD, n = 232/928), multinodular toxic goitre (MNTG, n = 91/364), solitary toxic adenoma (STA, n = 21/84). Patients diagnosed with hyperthyroidism within 1 year after delivery including post-partum GD were excluded. In multivariate conditional regression models (reference: no reproductive events), we analysed the association between development of GD/MNTG/STA and reproductive factors such as age at menarche/menopause, reproductive span, number of pregnancies/childbirths/abortions, investigations for infertility, and years on oral contraceptives. We adjusted for possible confounders such as alcohol intake, smoking, co-morbidity, and education. Age was studied as a potential effect measure modifier. Results: GD patients diagnosed before the age of 40 years had given births more often than control subjects (OR [95% CI] for 1/2/3+ births [ref.: nulliparous] were 1.57 [0.80–3.11]/2.06 [1.001–4.22]/3.07 [1.50–6.26]), and they had induced abortions performed more often (OR for 1/2+ induced abortions [ref.: no: events] were 0.99 [0.54–1.84]/2.24 [1.12–4.45]). No associations were observed between any reproductive factor and the development of MNTG or STA. Conclusions: Childbirths and induced abortions may be followed by development of Graves’ hyperthyroidism after the post-partum period. This was not the case for the non-autoimmune subtypes of hyperthyroidism.

MANAGEMENT OF ENDOCRINE DISEASE: Subclinical thyrotoxicosis: prevalence, causes and choice of therapy.

Subclinical thyrotoxicosis is a condition affecting up to 10% of the population in some studies. We have reviewed literature and identified studies describing prevalences, causes and outcomes of this condition. Treatment should be considered in all subjects if this biochemical abnormality is persistent, especially in case of symptoms of thyrotoxicosis or in the presence of any complication. In particular, treatment should be offered in those subclinically thyrotoxic patients with a sustained serum TSH below 0.1 U/L. However it is important to recognise that there are no large controlled intervention studies in the field and thus there is no high quality evidence to guide treatment recommendations. In particular, there is no evidence for therapy and there is weak evidence of harm from thyrotoxicosis if serum TSH is in the 0.1-0.4 IU/L range. In this review, we describe the different causes of subclinical thyrotoxicosis, and how treatment should be tailored to the specific cause. We advocate radioactive iodine treatment to be the first-line treatment in majority of patients suffering from subclinical thyrotoxicosis due to multinodular toxic goitre and solitary toxic adenoma, but we do generally not recommend it as the first-line treatment in patients suffering from subclinical Graves' hyperthyroidism. Such patients may benefit mostly from antithyroid drug therapy. Subclinical thyrotoxicosis in early pregnancy should in general be observed, not treated. Moreover, we advocate a general restriction of therapy in cases where no specific cause for the presumed thyroid hyperactivity has been proven.

The prevalence of thyroid cancer in patients with hyperthyroidism.

Objectives:To determine the prevalence of thyroid cancer in patients with hyperthyroidism.Methods:This is a retrospective observational study using the data of 71 Omani patients with a diagnosis of hyperthyroidism due to Grave’s disease, toxic multinodular goiter, and solitary toxic adenoma. These patients underwent thyroidectomy at the Royal Hospital (RH), Muscat, Oman, and were followed up at the National Diabetes and Endocrine Center (NDEC) between 2007 and 2013. The details were collected from the medical records of both the RH and the NDEC. Patients who underwent thyroidectomy for other reasons like non-toxic goiter and hypothyroidism with cancer were excluded from the study.Results:Thyroid cancer was identified in 32.8% (n=23) of patients with hyperthyroidism. Half of these patients 52.1% (n=12) had papillary micro-cancer (intra-thyroidal), and 3 patients with Grave’s disease (13%) had lymph nodes metastasis (loco-regional infiltration. The cancer preponderance was higher in young (n=21, 91.3%) and female patients (n=18, 73.9%). Most patients with thyroid cancer had abnormal ultrasound neck findings and thyroid scintigraphy (99 mTc uptake).Conclusion:Many patients with hyperthyroidism in Muscat, Oman, especially those with Grave’s disease, show malignancy, and hence a proper initial evaluation of these patients is required as part of long-term management.

The risk of malignancies in women with long flowing hyperthyroidism in history: a retrospective randomized study

The syndrome of thyrotoxicosis is the second occurrence in endocrine diseases giving way to the only diabetes. The most common cause of hyperthyroidism is Graves' disease. Nodular toxic goiter is following Graves' disease. Then more rare causes are solitary toxic adenoma and thyroiditis. Epidemiological studies carried out at the turn of XX-XXI centuries in the developed countries of Europe and North America have shown that a history of hyperthyroidism episode increases the relative risk of development of ovarian cancer by 80 % and breast cancer by 45-60 %. It has been shown that hyperthyroidism including subclinical one is a risk factor for morbidity and mortality from malignant neoplasms of different localizations as breast cancer, thyroid cancer, pancreatic cancer and lung cancer. In this case, drew the fact that significant differences in the risk of morbidity by specific disease forms depends on the ethnic composition of the population. In Russian Federation the similar epidemiological studies have not been carried out yet. We obtained the results of an epidemiological retrospective multicenter randomized clinical simultaneous analytical comparative study of the “case-control” among women treated for diffuse toxic goiter and nodular toxic goiter in 1999-2009. The study involved 1135 patients with hyperthyroidism in anamnesis. The comparison group included 953 patients with eu- and hyperthyroid status. The risk of malignancies in women with hyperthyroidism in anamnesis was 2.36 (95 % CI 1.63-3.42, p &lt; 0.01). The risk of hormone-dependent tumors was 2.65 ( 95 % CI 1.7-4.13, p &lt; 0.01). The aim: to evaluate the risk of malignancies in women with long flowing hyperthyroidism.

Incidence rate and clinical features of hyperthyroidism in a long‐term iodine sufficient area of Sweden (Gothenburg) 2003–2005

To study hyperthyroidism in long-term iodine sufficiency (IS), as iodine supply affects its occurrence. Prospective descriptive study. In 2003-2005, all referred cases of subclinical (SH) and overt hyperthyroidism (OH) were registered at diagnosis from a population (n = 631 239) in Gothenburg, Sweden. Information on age, gender, smoking, thyroid associated ophthalmopathy (TAO), thyroid hormones and TSH receptor antibodies (TRab) was collected. Incidences were calculated. SH and OH cases with Graves' disease (GD), toxic multinodular goiter (TMNG) and solitary toxic adenoma (STA) were compared. In GD, TRab+ and TRab- cases and patients with (TAO+) and without TAO (TAO-) were compared. The total incidence (n/100 000/year) of hyperthyroidism was 27·6; OH 23·8; SH 3·8; GD 21·4; TMNG 4·3; and STA 1·8. SH was more common among TMNG (40·2%) and STA (45·7%) than in GD (5·9%). SH-GD patients were older, more often smokers and had lower TRab levels than OH-GD patients. FreeT4 and T3 levels in GD were higher than in TMNG and STA. FreeT4, T3 and TRab decreased with age in patients with GD, P < 0·0001. TRab- patients had lower T3 than TRab+ patients, P < 0·001. TRab was positively correlated to FreeT4, P < 0·0001. TAO occurred in 20% of patients with GD. TAO+ patients were younger than TAO- patients. Smokers did not have more TAO. The total incidence of hyperthyroidism was low. GD dominated with an age-related decline of thyroid hormones and TRab levels. The spectrum of hyperthyroidism in this long-term IS area may represent the future situation for countries with shorter history of IS.

Adjuvant lithium improves the efficacy of radioactive iodine treatment in Graves' and toxic nodular disease

Lithium increases iodine retention in the thyroid gland and inhibits thyroid hormone release. Although lithium has been reported to improve the efficacy of radioactive iodine (RAI) treatment in Graves' disease, its role as an adjunct to RAI treatment of hyperthyroidism, particularly in toxic nodular disease, remains contentious. To assess whether adjuvant lithium increases the efficacy of a fixed dose RAI regimen in Graves' and toxic nodular hyperthyroid patients. Retrospective cohort study in a tertiary referral centre. Two hundred and four hyperthyroid patients (163 Graves' disease, 26 toxic multinodular goitre and 15 solitary toxic thyroid adenoma). One hundred and three patients received RAI alone (median dose 558 MBq). One hundred and one patients received RAI (median dose 571 MBq) with adjuvant lithium (800 mg/day for 10 days). Proportion of patients cured at any time over a 1-year period following RAI treatment. Cure was defined as sustained (two or more sequential time points) biochemical euthyroidism or hypothyroidism during the follow-up period. The likelihood of cure at any time was 60% greater in all hyperthyroid patients (Graves' plus toxic nodular disease) receiving adjuvant lithium (n = 204, P = 0·003). In patients with Graves' disease receiving RAI + lithium, there was a similar occurrence in cure (n = 163, P = 0·006). Cure was twice as likely in patients with toxic nodular (non-Graves') disease receiving RAI + lithium compared with RAI alone (n = 41, P = 0·01). This study supports the use of adjuvant lithium to improve the efficacy of RAI in the treatment of Grave's disease and suggests a novel role in the management of toxic nodular (non-Graves') disease.

Consultation with the Specialist: Thyroid Nodules

Based on strong research evidence, thyroid nodules in children and teenagers are more likely to be malignant than in adults. Based on strong research evidence, a history of ionizing radiation to the head or neck is an independent risk factor for the development of thyroid malignancies. There is strong research evidence, including a recent meta-analysis, supporting the use of fine-needle aspiration biopsy in the evaluation of all pediatric and adolescent patients presenting with a thyroid nodule. The surgical management and postoperative care of pediatric and adolescent patients who have well-differentiated thyroid carcinomas remains controversial, because the rarity of the disease limits the ability to conduct randomized, prospective research studies. Numerous studies have demonstrated that, despite presenting with more advanced disease, pediatric and adolescent patients with thyroid carcinoma have a higher survival rate than adults. The American Thyroid Association has issued strong evidence-based recommendations for the management of medullary thyroid carcinoma, including RET mutation testing and early prophylactic total thyroidectomy in children with high-risk mutations.

81st Annual Meeting of the American Thyroid Association SHORT CALL ABSTRACTS

81st Annual Meeting of the American Thyroid Association SHORT CALL ABSTRACTS

Incidence of hyperthyroidism in Sweden

The incidence of hyperthyroidism has been reported in various countries to be 23-93/100,000 inhabitants per year. This extended study has evaluated the incidence for ~40% of the Swedish population of 9 million inhabitants. Sweden is considered to be iodine sufficient country. All patients including children, who were newly diagnosed with overt hyperthyroidism in the years 2003-2005, were prospectively registered in a multicenter study. The inclusion criteria are as follows: clinical symptoms and/or signs of hyperthyroidism with plasma TSH concentration below 0.2 mIE/l and increased plasma levels of free/total triiodothyronine and/or free/total thyroxine. Patients with relapse of hyperthyroidism or thyroiditis were not included. The diagnosis of Graves' disease (GD), toxic multinodular goiter (TMNG) and solitary toxic adenoma (STA), smoking, initial treatment, occurrence of thyroid-associated eye symptoms/signs, and demographic data were registered. A total of 2916 patients were diagnosed with de novo hyperthyroidism showing the total incidence of 27.6/100,000 inhabitants per year. The incidence of GD was 21.0/100,000 and toxic nodular goiter (TNG=STA+TMNG) occurred in 692 patients, corresponding to an annual incidence of 6.5/100,000. The incidence was higher in women compared with men (4.2:1). Seventy-five percent of the patients were diagnosed with GD, in whom thyroid-associated eye symptoms/signs occurred during diagnosis in every fifth patient. Geographical differences were observed. The incidence of hyperthyroidism in Sweden is in a lower range compared with international reports. Seventy-five percent of patients with hyperthyroidism had GD and 20% of them had thyroid-associated eye symptoms/signs during diagnosis. The observed geographical differences require further studies.

Should we treat mild subclinical/mild hyperthyroidism? No

The management of a patient with subclinical hyperthyroidism or mild thyroid over-activity is controversial. Subclinical hyperthyroidism is defined as a serum thyrotrophin (TSH) below the reference range but a normal thyroxine (T 4) and triiodothyronine (T 3) level in a patient who is either asymptomatic or has only non-specific symptoms. Epidemiological studies report an overall prevalence of approximately 3%, with men and women over 65 years and those in iodine deficient regions having the highest prevalence. Approximately 50% of subjects are taking levothyroxine. The aetiology for those with endogenous subclinical hyperthyroidism is Graves' disease, toxic nodular goitre or rarely a solitary toxic adenoma or thyroiditis. Non-thyroidal illness is an important cause of false positive low serum TSH test results. Subjects with low but detectable serum TSH values (0.1–0.4 mU/L) usually recover spontaneously when re-tested. It has been estimated that in those with an undetectable serum TSH (< 0.1 mU/L) conversion to overt hyperthyroidism occurs at a rate up to 5% per year. Advocates of intervening for subclinical hyperthyroidism argue that early treatment might reduce mortality, prevent the later development of atrial fibrillation, osteoporotic fractures, and overt hyperthyroidism but data supporting improvement in outcomes are sparse. No appropriately powered prospective, randomised, controlled, double-blinded trial of intervention for subclinical hyperthyroidism exists. For the vast majority of patients adopting a “wait and see” policy rather than intervention may avoid unnecessary treatment or the potential for harm. Any potential benefits of therapy in subclinical hyperthyroidism must be weighed against the significant morbidity associated with the treatment of hyperthyroidism.

Epidemiology of subtypes of hyperthyroidism in Denmark: a population-based study

Few population-based studies have described the epidemiology of subtypes of hyperthyroidism. A prospective population-based study, monitoring two well-defined Danish cohorts in Aalborg with moderate iodine deficiency (n=311 102) and Copenhagen with only mild iodine deficiency (n=227 632). A laboratory monitoring system identified subjects with thyroid function tests suggesting overt hyperthyroidism (low s-TSH combined with high s-thyroxine or s-triiodothyronine). For all subjects, we collected information on medical history, thyroid scintigraphy and thyroid hormone receptor antibody (TRAb) measurement. Information was used to disprove or verify primary overt hyperthyroidism and to subclassify hyperthyroidism into nosological disorders. From 1997 to 2000 (2 027 208 person-years of observation), we verified 1682 new cases of overt hyperthyroidism. The overall standardized incidence rate (SIR) per 100 000 person-years was 81.6, and was higher in Aalborg compared with Copenhagen (96.7 vs 60.0, P<0.001), giving an SIR ratio (SIRR (95% confidence interval (CI))) between moderate versus mild iodine-deficient areas of 1.6 (1.4-1.8). Nosological types of hyperthyroidism (percentage/SIRR (95% CI)): multinodular toxic goitre (MNTG) 44.1%/1.9 (1.6-2.2), Graves' disease (GD) 37.6%/1.2 (0.99-1.4), solitary toxic adenoma (STA) 5.7%/2.4 (1.3-3.5), 'mixed type' hyperthyroidism (TRAb-positive, scintigraphicly multinodular) 5.4%/6.0 (3.0-12), subacute thyroiditis 2.3%/0.9 (0.4-1.4), postpartum thyroid dysfunction 2.2%/1.6 (0.8-3.0), amiodarone-associated hyperthyroidism 0.8%/7.1 (1.1-65), hyperthyroidism after thyroid radiation 0.7%/12.3 (0.8-50), lithium-associated hyperthyroidism 0.7%/0.97 (0.4-4.8) and hyperthyroidism caused by various other factors 0.7%. Lifetime risk for overt hyperthyroidism was 10.5%/6.5%/2.4% (females/all/males). Hyperthyroidism was common in Denmark with MNTG and GD as dominating entities. The higher incidence of hyperthyroidism in the most iodine-deficient region was caused by higher frequency of MNTG, 'mixed-type', STA and amiodarone-associated hyperthyroidism.

Fixed dose (555 MBq; 15 mCi) radioiodine for the treatment of hyperthyroidism: outcome and its predictors

Radioiodine therapy (RIT) is an accepted treatment for hyperthyroidism and a 555-MBq (15-mCi) dose is frequently used. We aimed to assess treatment outcome with this dose, and to identify predictors of successful treatment. An analysis of 478 treated patients demonstrated an overall four-month cure rate of 79.5%; success rate was higher in patients with toxic multinodular goitre, solitary toxic adenoma, a smaller thyroid or less severe disease. This information may be of further assistance if variation in the dose of RIT is considered.